The mechanism of activation of glycogen synthesis by isolated rat hepatocytes will be studied. Inhibitors of amino acid metabolism and of reactions involving glutamine will be employed to localize the site of action. We will determine whether amide group transfer from glutamine is involved in the activation of glycogen synthesis and glycogen synthase. The concentration of organic and amino acids in the mitochondria and cytosol of cells incubated with glutamine, mercaptopicolinic acid, and azaserine, will be determined. We will try to determine what compounds derived from glutamine activates glycogen synthesis. The use of tritium labeled water to measure the pathways of glycogen synthesis and degradation will be explored. Incorporation of 3HOH into glycogen may serve to determine the relative incorporation of glucose and gluconeogenic precursors into muscle glycogen. Incorporation of 3HOH into glucose during glycogen breakdown may serve to establish the relative roles of phosphorylase and amylase plus glucosidases in the breakdown of glycogen induced by anoxia and hormones.